Doubt about my A/F Ratio
 

Hi everyone,

I have UpRev Cipher which I use to monitor the sensors in my Z and took advantage of the on-board wideband O2 sensors to check how my A/F ratio is during cruising and during acceleration all the way to red line..

My doubt starts here:
I've read many times throughout forum posts that as you install breathing bolt-on mods you end up having a leaner mixture..

AFAIK, the lower the number on the A/F ratio reading means it's RICH and the higher the number on the A/F ratio reading means it's LEAN.

So, during idle, for example, my A/F ratio is in the 14-15 range which is cool..

The thing is, when I push on the pedal and take it to red line my A/F ratio starts getting richer, and richer, and richer... At around 7,000rpm I'm looking at an A/F ratio of 10-11... IS THIS NORMAL?

Also, I noticed than when I let off the pedal and let the engine start decelerating, the A/F ratio bumped up and maxed out at constant 30. IS THIS NORMAL..??

I appreciate your comments and thanks in advance!

getting 10-11 AFR at 7000rpm is way to rich !!

and if you let off the pedal which mean you stop fuel delivery , the result of this is you get only air reading ( 30 which is probably the limit on your sensor)

10-11 at 7k seems a bit rich.

here's a couple of stock tuning dynos with AF ratio

http://www.the370z.com/forced-induct...-vert-6mt.html
http://www.the370z.com/intake-exhaus...o-results.html

I forgot to mention (although you can read it in my sig) I have Stillen G3 intakes, Berk HFC's and Stillen CBE...

I dont see those mods affecting you a/f much. Most n/a motors find the sweet spot between 12.5 - 13.0. If your dipping below 11.9 that high n/a, you are leaving some power on the table.

Edit: and the a/f bouncing around and maxing out when you let off the gas is normal.

Thats a bit rich at wot. The high afr during deceleration is normal. Once you hit idle our put load back on the car it should dip back down

Hey just to let you know and hopefully this information helps you. Sam@GTM has told me multiple times to not put full faith in cipher's AFR. He said it is good enough to give you a idea on your AFR but not to think that is the actual because the table in there that computes it, is not that great. Hope this helps with putting you at ease a bit
Frank

Thanks for your comments guys!

Thanks for this info.. Do you by any chance have an idea on what is the approximate difference between Cipher and the real numbers..??

Thanks again!

No I do not. Sam would no since he has ran the cipher against a AFR guage if i remember right

on my car and my Innovate AFR gauge ,, Cipher read about .3-.5 AFR richer depending on the RPM than the aftermarket sensor

example;
Cipher @ 7000 rpm = 12.9
AFR sensor @ 7000 rpm = 13.4

That's good to know.. Thanks for your input..

My Cipher reads around 10-11 @7000rpm so even with a .5 difference I'm still running rich @ WOT..

The sad thing is, there are no Dyno's in my country and no UpRev certified tuners.. How great is that? :ugh2:

i had injenCAI and berk HFC and i was running rich b4 custom tune

AFR's
 

Hi Guys, my Cipher software gives me a voltage output instead of the actual AFR, do you know how to get Cipher to show the AFR instead of the voltage?

These are the same results I have found as well. Also with boosted cars they are scaled off a lil further then that actually. For whatever reason on the 370's Nissan switched back to a 4 wire wideband which isn't as accurate as a 5 wire in my experience.

That is probably because UPREV does have your ROM converted yet to set up the A/F Sensor scaling in cipher.


As far as the OP goes, I have seen stock Z's dip down that rich close to redline. If interested we offer E tuning and can get you tuned via E tuning and take care of the air fuel issue.

Hey Vince,

Managed to get the AFR readings back - had to reload Cipher. Still battling with the hot start issues. Car starts perfectly when cold. Idles and runs perfectly. As soon as the water temp goes over 20 degrees C, the car won't start unless I help it with the Accellerator pedal. Apparantly there is a new patch coming out for the ROM editor which gives more tables for the cranking fuel enrichment - Omar at Uprev as reference.

I have the GTM stg 1 SC. Our altitude is 6000 ft.

I see I get a 14% fuel correction at idle to get it to target idle AFR. Looks like it is adding fuel to get it to idle. Not sure what this will mean for cranking enrichment.

Your advice will be appreciated.

This is a very annoying poblem to have - having your car not fire up in the parking lot, with all the M3 drivers laughing at your car...:roflpuke2: